I guy gave me 6 IF amplifier Pentode tubes today (4BZ6)  he had as surplus, basically from a batch of random tubes he ordered off ebay and said they weren't useful for any existing devices that he works on....so he gave me six of them to play with.  He said he had something going once that sounded very Marshall-ish by playing around with the heater voltages.

Anyone ever hear of these?  Ideas are welcome if you guys have some favorite tube amp circuit snippets that I could use and re-vamp for these pentode tubes.  I'm getting kind of excited to try them out.  They will operate on some fairly low voltages for pentodes, so it makes them convenient for stompbox overdrive circuits.

I found a tube site today that had some 6BG6c's for sale real cheap, and a adapter that lets you slip them in a amp that use's the 6L6 style tube's, he say's they will handle up to 700 v. on the plate's, got the same heavey plate's that are in the 7589 tube that i love so much, he say's they sound just as good as a 7589, i'm ordering 6 matched with adaptors for my Peavey Mace, and he has tested these for hour's on his own equipment with no failure's,
http://www.vacuumtubes.com/
Johnny

tinkering with tubes is fun.  I just subbed a 12AU7 for a 12AX7 in the drive channel in my amp today and it produces a much more creamy/mushy....how do you describe it? It's a softer distortion.  Obviously much less gain so it doesn't drive quite as hard, but it's a sound closer to what I want out of a tube amp.  If I want metal tone, I'll buy a Mesa or Peavey 5150 or something.  

I'm using the Peavey classic duel 212.  It's a sweet amp, I think.  It has a fine sound in the clean channel, and a lot of potential for the drive channel now that I have the 12AU7's in there.  I just need to do a few mods and I think it will be about perfect.

Either way, the preamp is pretty generic in the Peavey, so it wouldn't be hard to take the basic design with better tailored mods and build it into a stompbox with more customized options.  I may even be able to make a fair JFET version of it if I like what I hear.  It's just hard to make FETs sound like softer-clipping tubes.  The transfer curve is more like a pentode.

My old Classic 2X12 Peavey which is an old black amp will get some mod's too !, it has a Jfet pre-amp already in it, in the form of TL072's, afew ca3094's and a couple 4558 ic's, all this is good but when you look at the lil ugly capacitor's they used to voice the amp with and couple the circuit's, you wonder how it ever get's any tone, i'm gonna experment with better quality cap's and see if it make's a diff.
yeah, the sky's the limit on these amp's, you can have some fun,
Johnny

I haven't noticed that any of the caps in my amp are that bad.  There are a couple electrolytics for coupling, but most of them are 500V metalized poly-film capacitors.  

Is that solid state stuff (4558's, CA3094's, etc.) part of a circuit you built, or is it part of the amp's circuit?  My amp (Peavey Duel) is actually all vacuum tube amplification.  The only part of the circuit that the signal touches anything solid state is in the reverb- tank driver, where they have a little BJT amplifier (basically a discrete component op amp), and the reverb tank gain recovery amplifier is solid state, none of which are distorting...oh, and there are some reverse-biased diodes at the power amp output for circuit protection puposes.  The only thing they would add is a couple pF capacitance, which at the impedances seen on the output, would not have an audible effect.

My desired mods are to change capacitance values in the drive channel to get a brighter, less muddy sound.  I want it to be more like a Vox.

I also want to make a reverb tank feed-back to see if I can get a little longer decay.  I'm not sure if this will work, or if it will just go unstable but it's worth a try anyway.

...yeah,

Quote...the sky's the limit...

The amp Johnny's talking about it the classic vt- and earlier design that had a solid state front end with a tube power amp. I have one of those and I have to admit,,,,,,,I kind of like it :oops:
Regan